Sector: A sector is a part of a circle.
Chord: A chord is a straight line connecting two points on a circle.
Diameter: A diameter is a straight line passing through the center of the circle and touching two points on the circle.
Diagonal: A diagonal, on the other hand, is not specific to circles; it refers to a line connecting two non-adjacent vertices of a polygon.
Therefore, the correct group consists of 1, 2, and 4.
An object is said to have an n-fold rotational symmetry if the object, rotated by an angle of \( \frac{2\pi}{n} \), is identical to the original.
Which one of the following objects exhibits 4-fold rotational symmetry about an axis perpendicular to the plane of the screen?
A color model is shown in the figure with color codes: Yellow (Y), Magenta (M), Cyan (Cy), Red (R), Blue (Bl), Green (G), and Black (K). Which one of the following options displays the color codes that are consistent with the color model?